To sacrifice something is to give it away, often to prevent a larger evil or to achieve a greater benefit. In primitive cultures where the word originated, it means you make something sacred by dedicating it to the gods for their use alone. You do this typically by preventing it ever being used by anyone else, i.e. you kill it or destroy it. It may be a young child, or a prisoner, or a prized horse or farm animal, or a sword or jewelry. You invoke the gods, then kill or break the sacrifice, or throw it somewhere irretrievable like the sea or a volcano.
Here’s a story out of rural India, reported in the Sydney Morning Herald:
A seven-year-old Indian girl was murdered in a tribal sacrifice and her liver offered to the gods to improve crop growth, police in the central state of Chhattisgarh said on Sunday.
The body of Lalita Tati was found in October a week after her family reported her missing.
“A seven-year-old girl was sacrificed by two persons superstitiously believing that the act would give a better harvest,” Narayan Das, the police chief of Bijapur district, told AFP by telephone.